Zafrira Nitsan

Growth and development of the digestive organs and some enzymes in broiler chicks after hatching

1. Body weight and the weight of the digestive organs and activities of some digestive enzymes were determined from hatching to 23 d of age. 2. Relative daily growth rate peaked at 11 d of age (22% gain/d) and then decreased gradually. 3. The vitelline residue was decreased rapidly from 4.6 g at hatching to negligible values from 4 d of age. 4. Maximal allometric growth of the pancreas and small intestine was 4-fold and that of liver 2-fold greater than that of the body. 5. Activities (units/kg body weight) of the digestive enzymes measured in the pancreas and intestinal contents increased with age. In the pancreas maximal values were attained on day 8 for amylase and lipase and 11 for trypsin and chymotrypsin. In the small intestine maxima were attained on day 4 for lipase, 11 for trypsin and chymotrypsin and 17 for amylase. 6. The development of secretion of digestive enzymes in the post-hatched chick could be a limiting factor in digestion and subsequently in food intake and growth.

Comparative growth and development of the digestive organs and of some enzymes in broiler and egg type chicks after hatching

1. Body weight, the weight of digestive organs and activities of some digestive enzymes were determined from hatching to 14 d of age in meat- and egg-type chickens. 2. Relative daily food intake and growth rate were much higher in meat- than in egg-type chickens. Relative daily food intake peaked at 30% of body weight at 3 d of age in meat-type, and at 20% of body weight at 6 d of age in egg-type chickens and then decreased gradually. The corresponding values for growth rate were 20 and 14%. 3. Allometric growth of the small intestine, intestinal contents and liver was greater in meat-type chickens, but the growth of the pancreas attained a higher value in the egg-type birds. Diminution of the vitelline residue was similar in the two breeds. 4. Pancreatic digestive enzyme activities were similar between stocks, but activities in the small intestinal contents were lower in meat-type chickens. 5. The secretion of digestive enzymes in the newly-hatched meat-type chicken could be a limiting factor in digestion and, consequently, in food intake and growth.

Goats fed tannin-containing leaves do not exhibit toxic syndromes

Abstract The blood metabolic profile was examined in 2–3 year old non-lactating and non-pregnant Mamber goats consuming Quercus calliprinos (oak), Pistacia lentiscus (pistacia) and Ceratonia siliqua (carob) leaves to determine whether intake of tannin-rich fodder induces subclinical systemic toxicity. Total phenolic and condensed tannin content ranked in the order pistacia > oak > carob. Goats did not exhibit toxic effects following consumption of 10–23 g kg −1 day −1 of tannin-rich leaves. Metabolite blood concentrations did not differ from goats fed wheat straw, and were within the normal range. Certain serum metabolic indices that are known to be sensitive indicators of damage to the liver (gamma glutamyltranspeptidase, alkaline phosphatase, cholesterol) and kidneys (urea, uric acid, minerals) were within the normal range for goats. Thus, it appears that goats used in this study were well adapted to the nutritional environment and may consume large amounts of tannins (1.1–2.7 g per kg BW per day condensed tannins and 0.4–0.9 g kg −1 BW day −1 soluble phenolics) without suffering any ill effects.

Influence of overfeeding on growth, obesity and intestinal tract in young chicks of light and heavy breeds.

1. Heavy-breed (HB) chicks differed from light-breed (LB) ones in their propensity to be overfed. Whereas in the LB chicks the amount by which they could be overfed reached 70% more than the food consumed daily by the ad lib.-fed chicks, in the HB chicks the maximal excess was only 13%. 2. Overfeeding caused a slight but statistically significant increase in the linear growth rate (shank length) of the LB chicks, with an opposite effect in the HB chicks. 3. Overfeeding increased the weight of the crop, proventriculus, small intestine, pancreas, liver and adipose tissue but had no such effect on the heart, cerebrum or cerebellum. 4. Overfeeding had no effect on the specific activities of the pancreatic digestive enzymes, liver xanthine dehydrogenase, or tryptophan oxygenase (EC 1.13.1.12). The increase in the total activities was due entirely to organ hypertrophy. 5. Obesity induced in young chicks had no residual effects on the adult LB chicks, but reduced the linear growth of the adult HB chicks. 6. An explanation for the difference between breeds in response to overfeeding at an early age is discussed.

Interactions among tannins, supplementation and polyethylene glycol in goats given oak leaves: effects on digestion and food intake

Effects were studied on food intake and diet apparent digestibility of giving to goats once daily a basal diet rich in tannin from inclusion of leaves of Quercus calliprinos either supplemented with a high carbohydrate or a high protein food. Also interactions with polyethylene glycol (PEG) were investigated. The results of the present work confirmed our presumption that the content of tannin in some Mediterranean browse is so high that it may negatively affect the utilization of protein in supplementary foods. Neutralizing the tannins with once-daily provision of PEG proved to be an effective means of preventing the negative effect. Providing 10 g/day PEG to goats given Quercus calliprinos leaves ad libitum and supplemented with 300 g/day concentrates containing 160 g crude protein per kg DM increased digestible crude protein intake by 50 g/day. When the concentrate food was given to goats, leaf dry-matter intake decreased significantly (from 664 to 565 g/day) and the goats lost weight rapidly. Therefore, supplementing tannin-rich leaves with concentrate food is recommended only if done in combination with PEG. High protein supplementation increased leaf (from 664 to 844 g/day) and digestible protein intakes (from 4·8 to 92·3 g/day) but a considerable portion of the protein supplementation was wasted due to interaction with tannins. PEG may allow economies in the use of such high-cost foods due to the greater efficiency of protein utilization (digestible crude protein intake increased from 92·3 to 122 g/day) of the supplementary food and to increased intake and protein utilization of the basal leaf diet (from 844 to 1023 g/day).

Short-term changes in eating patterns explain the effects of condensed tannins on feed intake in heifers☆

Ingestion of condensed tannins decreases feed intake in ruminants. Polyethylene glycol (PEG) forms high-affinity complexes with tannins. In two experiments carried out on Holstein heifers, quebracho (Q) from the Aspidosperma quebracho served as source of condensed tannins. The aims of the study were (i) to quantify the effect of Q on feed intake and eating behaviour in cattle fed complete mixed diets (CMDs); (ii) to clarify if changes induced in ingestive behaviour and feed intake by Q in cattle can be reversed by feeding PEG; and (iii) to clarify if the decrease in feed intake is associated with short-term (astringency, post-ingestive malaise) or longer-term effects. In experiment 1, 500 g/day of Q was found to be the minimal dose that decreased feed intake in heifers. A ratio of PEG:Q equal to 1:12.5 did not fully restore feed intake. In experiment 2, four heifers received a random sequence of four rations in a Latin-square design with feeding cycles of ca. 7 days: CMD containing no supplements (C), or supplemented with 625 g/day of Q without PEG (Q), with 625 g/day of Q and 250 g/day of PEG (Q-PEG), or with 250 g/day of PEG without Q (PEG). Individual rations were continuously weighed in the trough and the behaviour of heifers was observed for 180 min after distribution of CMD. Overall, feeding Q was associated with lowered feed intake and shorter duration of eating bouts, mainly of the first eating bout, immediately after distribution of the diet. A larger portion of the diet was consumed subsequent to 180 min after distribution in Q-fed heifers. Eating rate and the water to food ratio were not affected by Q. The effects of Q on feed intake were attenuated by feeding PEG. Heifers adapted effectively to condensed tannins by increasing the number of eating bouts and the portion of diet consumed subsequent to 180 min after distribution, so that no differences in feed intake were noted on the last day of each feeding cycle. Data are interpreted to show that: (i) negative effects of Q on feed intake derive from astringency of CT and short-term post-ingestive malaise; (ii) the increased number of eating bouts and their wider partition throughout the day are means to preserve the ruminal environment in Q-fed heifers; (iii) PEG has the potential to neutralize negative effects of condensed tannins in cattle.

Increasing productivity in goats grazing Mediterranean woodland and scrubland by supplementation of polyethylene glycol

A single daily oral dose of polyethylene glycol (PEG) — a tannin-binding agent — has been shown to substantially improve feed intake and efficiency of utilization by sheep and goats consuming tannin-rich forage. The aim of this study was to quantify the effect of supplementing 10 g/day of PEG on the performance of does grazing on Mediterranean woodland and scrubland. The experiments were carried out in production systems based on Mamber goats raised only for the production of slaughter kids (Experiment 1), dual-purpose Mamber goats raised for slaughter kids and milk (Experiment 2) or DamascusAnglo-Nubian goats raised mainly for milk (Experiment 3). In Mamber goats, PEG supplementation was associated with higher body weight (BW) gain during pregnancy (p<0.01), higher kid birth-weight (p<0.05) and daily BW gain until weaning (p<0.10 and p<0.05 in Experiments 1 and 2, respectively), and no difference in milk yield. In contrast, the response of DamascusAnglo-Nubian goats to PEG was a 43% increase in milk yield (p<0.001) but no response in kid weight at birth. These responses are consistent with previous findings that show the resilience of Mamber goats to practices aimed at increasing their milk production while these goats respond well to practices that improve the probability of successful reproduction in harsh environments. In contrast, DamascusAnglo-Nubians respond to increased available nutrients by increasing their milk production. Supplementation with PEG has the potential to improve the profitability of systems in which liberally supplemented and high-yielding dairy goats feed on Mediterranean browse. However, its contribution to production systems exploiting well adapted but low-yielding local goats is limited. # 2000 Published by Elsevier Science B.V.

The effects of force-feeding on enzymes of the liver, kidney, pancreas and digestive tract of chicks

1. Force-feeding of young chicks for 15 d increased kidney arginase ( EC 3·5·3·1) activity threefold. Fasting for 30 h decreased this activity by 50%. 2. Liver xanthine dehydrogenase was slightly increased after force-feeding and decreased following fasting. 3. The specific activities of two pentose-phosphate-cycle enzymes were not significantly affected by force-feeding, but glucose-6-phosphate dehydrogenase ( EC 1.1.1.49) decreased following fasting. 4. The over-all secretion of digestive enzymes increased parallel to the increase in food consumption. Therefore, despite an increased absolute weight of the pancreas and intestinal chyme, specific activities were the same in the force-fed and ad lib .-fed groups, except for a higher activity in intestinal amylase. 5. Fasting did not affect the pancreatic enzymic activities.

Aspects of food intake restriction in young domestic fowl: metabolic and genetic considerations

This paper reviews the literature on the response of young domestic fowl to various food restriction patterns. Emphasis has been given to anatomical, endocrine and immunological factors and their interactions with the genetic background. Under restricted feeding (limitation of the amount or time of access to food) chickens learn quickly to ingest the allocated quantity of food within a short period of time. When exposed to a single sequence of food removal and restoration, body weight losses are reduced for non-adapted compared with adapted individuals, for light breeds compared with heavy breeds, and for older compared with younger chickens. Adaptation to food restriction includes increased capacity and slower evacuation of the gastrointestinal tract (mainly the storage organs) to increase the supply of nutrients during the periods of food deprivation; increased hepatic lipogenesis and glycogen synthesis during the feeding cycle; and decreased heat loss on days of food deprivation. Synthesis and secretion of digestive enzymes in response to intermittent feeding has been found to be population dependent and consistent with the hypothesis that the amount of intestinal chyme mediates the synthesis and excretion of digestive enzymes from the pancreas. Numerous hormones are directly or indirectly involved in the metabolic responses to food restriction. Hyperinsulinaemia, increased plasma levels of growth hormone, triiodothyronine, thyroxine and plasma prolactin have been observed after the reintroduction of full feeding. It is suggested that the altered hormonal environment induced by food restriction contributes to a metabolic situation that may enhance immunocompetence.

The relative growth of internal organs in light and heavy breeds

The relative weights of the gastro-intestinal segments and of some other internal organs from light and heavy breed chicks from hatching to 21 days of age were compared. 2. The relative weight of the duodenum and jejunum was higher in the light breed than in the heavy one, the reverse relationship was found for the ileum and caecum. 3. The relative growth of the pancreas, heart, cerebrum and cerebellum was greater in the light breed.